Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!1.eu.feeder.erje.net!newsfeed.xs4all.nl!newsfeed1a.news.xs4all.nl!xs4all!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.000 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; 'example:': 0.03; 'win32': 0.03; 'subject:: [': 0.04; 'subject:Python': 0.06; 'class,': 0.07; 'practice,': 0.07; 'builtin': 0.09; 'cc:addr:python-list': 0.11; 'python': 0.11; 'from:addr:p.f.moore': 0.16; 'from:name:paul moore': 0.16; 'subclasses': 0.16; 'subject:Dev': 0.16; 'wrote:': 0.18; 'bit': 0.19; 'subject:] ': 0.20; 'feb': 0.22; '>>>': 0.22; 'cc:addr:python.org': 0.22; 'cc:2**1': 0.23; 'simpler': 0.24; 'paul': 0.24; 'define': 0.26; 'pass': 0.26; 'header:In-Reply- To:1': 0.27; 'message-id:@mail.gmail.com': 0.30; 'skip:( 20': 0.30; '>>>>': 0.31; 'names.': 0.31; 'such.': 0.31; 'class': 0.32; 'something': 0.35; 'received:google.com': 0.35; 'wrong': 0.37; 'bad': 0.39; 'more': 0.64; 'to:addr:gmail.com': 0.65; "'3'": 0.84; '2015': 0.84; 'shadow': 0.84 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=YH1M5cLDGvH1zabK/G+oVQICnpoAF2hEe/mj8R02Lk0=; b=MQ6DN2r63ANlcWQ7fCq46OYjYy4hBCvIAzEbKDJ3Oe65GvMlXCsnZu9AaRTNQgWj40 FhBCle9WafvE9gg6T3ZpDjvDKPHVBUUEmiJr5Ou6jkdxOHPQjin8j+2btFyenteTQX+r NrYYuJXi+CJK7f7766jQl3rehwsssVTAKEXAu36J12/8OjHmWEjEbJucPdUzvEX0B7+8 Q8Q8jVFrkC+2/3LLGQclMaUm60eiNH8sc2E+6b/DEGjcHt0yvCYzmRRkmi63eVqe/RAw EVbwOfo+9An09cpMSE6D+mz6Wkcl8FtUWPEw+cTcCtdFcx+zI1eec198fIYEMlz8BJnT fQ9A== MIME-Version: 1.0 X-Received: by 10.60.175.72 with SMTP id by8mr7256884oec.35.1431331944884; Mon, 11 May 2015 01:12:24 -0700 (PDT) In-Reply-To: References: Date: Mon, 11 May 2015 09:12:24 +0100 Subject: Re: [Python-Dev] anomaly From: Paul Moore To: Mark Rosenblitt-Janssen Cc: "python-list@python.org" , Python Dev Content-Type: text/plain; charset=UTF-8 X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.20+ Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Newsgroups: comp.lang.python Message-ID: Lines: 25 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1431331954 news.xs4all.nl 2922 [2001:888:2000:d::a6]:43357 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:90358 On 10 May 2015 at 17:34, Mark Rosenblitt-Janssen wrote: > Here's something that might be wrong in Python (tried on v2.7): > >>>> class int(str): pass > >>>> int(3) > '3' It's not wrong as such. It is allowed to define your own class that subclasses a builtin class, and it's allowed to shadow builtin names. So while this is (obviously) bad practice, it's not wrong. For a simpler example: Python 3.4.3 (v3.4.3:9b73f1c3e601, Feb 24 2015, 22:44:40) [MSC v.1600 64 bit (AMD64)] on win32 Type "help", "copyright", "credits" or "license" for more information. >>> str >>> str = "Hello" >>> str 'Hello' Paul